Pneumatic hammer.



J. T. McGnATH. PNEUMATIC HAMMER:

(Application filed Jan. 11, 1902.)

" Patented mpv. 25, |902."

` Ulo Model.)

UNITED STATES` PATENT OEEICE.

PNEUMATIC HAMMER.

SPECIFICATION forming part of Letters Patent No. 714,321, dated November 25, 1902. Application led January 11, 1902. Serial No. 89,345. (No model.)

To @ZZ whom t may concern,.-

Be it known that I, JOHN THOMAS Mo- GRATH, master mechanic, of the town of Fort Gratiot, in the county of St. Clair, in the State of Michigan, have "invented ctr-t .in new and useful Improvements in Pneu "atic Hammers,"of which the following is l specica- My invention relates to improvements in pneumatic hammers; and the object of the present invention is to devise a pneumatic hammerwhichwill have a maximum efficiency or power for aminimum use of air and which will also have a maximum rapidity of action, and thereby be not only most economical, but have a maximum power for a givenV size of hammer; and it consists, essentially, of a stock or casing in which the tool is placed, a piston provided with a tapered upper end and inlet-valves the stems of which are designed to extend into the cylinder, so that the hammer in its upward stroke contacts with same and opens the valve for the admission of air to produce a rapid stroke of the hammer, the inlet-valves and passage-ways and parts being arranged and constructed in detail as hereinafter more particularly explained.

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Figure 1 is a sectional view of my improved hammer. Fig. 2 is an Aenlarged detail of the piston. Fig. 3 is an enlarged detail of the valves,showing portion of the cylinder broken away to'exhibit the passage-ways around the valves and leading into the cylinder. y

In the drawings like characters of reference indicate corresponding parts in each gure.

A is the stock or casing of the hammer, Which is formed integral from end to end and hollow, as shown.

A is the usual handle, `which is formed at the upper end of the casing or stock. i h is the tool-holder in which the tool A2 is a is the passage-way into which the end of the tube extends by which the air is supplied to the chamber. The air passage-wayextends inwardly into the annular recesses bin the screw-plug B at the upper end of the hammer.

c is the passage-way leading from the valvechamber C into the annular recess b.

c is a passage-way leading from the end of the valve-chamber into the aun 111er 'L :cove b.

C' is .the plug closing the end'of'the valvechamber, and C2 is a valve provided with the usual stem c2 and operating-trigger c3. The annular recess b' communicates with the passage-way b2, which communicates with the longitudinal passage-way a' in the casing.

a2 is a passage-way leading from the opposite end of the passage-way a into the interior of the casing opposite the piston D. (See dotted lines, Fig. 1.)

The piston D is provided with a recess d and a hole d', extending outwardly therefrom, and an annular enlargement d2 at the top, which is tapered at the extreme end at d3, as shown. The interior of the casing is provided with an inwardly-extending annular enlargement or shoulder a3, through which the piston extends.

a4 is an annular groove in the cylinder near the enlargement or shoulder a.

a6 represents exhaust-holes in the lower portion of the chamber.

2 represents dislrvalves provided with stems 3, such valves being located in the chamber 4 and the stems 3 of the same extending into the cylinder at a point substantially on a line with the smallest diameter of the tapered end d3 of the piston D.

5 represents a series of holes surrounding the stem of the valve and extending from inside of the disk 2 of each valve into the interior of the piston. The upper portion of the chamber in which the piston reciprocates is provided with a shoulder a7, so that the diameter of the upper end is slightly increased. The stems 3 of the valves are held in guiding-sockets 6 in the screw-plug 7, the inner ends of which form the outer wall of the valve-chambers 4.

8 is a passage-way leading from the passageway c into one valve-chamber Il, and 9 is a passage-way leading from the passage-way a, into the opposite valve-chamber 4.

Having now described the principal parts involvedin my invention, I shall brieiiy describe its operation and utility.

In the operation of the hammer the air is admitted through the passage -way a and passes around the annular recess b' through the passage-way c. When the hammer has been broughtinto position for work, the valvestem is pushed inwardly by means of the trig- The piston is shown in the position y ger c3.

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y the piston 4through the passage-ways 5 into the cylinder, `thereby forcing such piston down and at the same time passes into the opening a2. When has reached the point where the passes the annular enlargement a3, exhaust-s through the openings 0L at hole d' the air t the lower end of the cylinder, and this of `ment of the cylinder, and therefore as course takes place when such piston reaches or is reaching the limit of its downward stroke. At the same time that the airis admitted past the valves 2 the air also is being admitted by means of the passage-ways b2, a', and a2 into the space in the cylinder between the upper end d2 of the piston and the internal enlargesoon y as the pressure of the air (fz-,rees the valves 2 to close the passage-ways; leading into the cylinder, the piston which has received its `impetus and is reaching the limit of its stroke will upon reaching such limitbe forced back- Wardly again by the compressed air between Y the enlargement cl2 of the piston and internal and, in fact,

Athe uppere'nd enlargement@s of the cylinder, as the air at of the cylinder will have then been exhausted through the holes d and a.

The operation is of course repeated, and I find in practice is very rapid and ecient,

so much so that I can obtain more power and do more work with my pneumatic hammer than with other hammers the stroke of which is nearly double the length to that of mine.

` What I claim as my invention is 1. In a pneumatic hammer, the combination with a casing having a supply-passage for air provided with a main colzitrolling-valve, said casing having ports for admitting air in rear of the piston, check-valves controlling said ports and having stems projecting into the casing, a piston within the casing having inclines for contacting with said stems to raise the valves from their seats to admit air and propel the piston, means for admitting air to the opposite side of the piston to return it to initial position, and means whereby the air is exhausted from t-he cham ber, substantially as described. v

2. In a pneumatic hammer, in combination a casing or stock provided with passage-Ways and main valve for the admission of air, said casingbeingprovided with anannularinterior enlargement forming a reduced portion or shoulder intermediate of the length of the cylinder, a piston of the same diameter as the reduced portion and provided with a head of corresponding diameter to the major portion of the interior of the cylinder, said head bcing tapered at the upper end, disk valves 1ocated in suitable chambers in the wall of the cylinder and havinga stem extending through the walls into the path of the tapered end of the pistons, passage-Ways leading through the wall of the cylinder from inside the disks of the valves, and passage-Ways leading from the main admission passage-ways into the valve-chambers as and for the purpose speoitied.

JOHN THOMAS MCGRATH. Witnesses:

B. E. SHARP, CEAS. E. KEAN. 

